APEX FY2000 Task II: Exploration of High Payoff Liquid Walls - Liquid MHD Modeling and Experiments

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Conrad Logan
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1 APEX FY000 Task II: Exploration of High Payoff Liquid Walls - Liquid MHD Modeling and Experiments Task Leader: Neil Morley Contributors: M. Abdou, J. Burris, B. Freeze, H. Huang, M. Kotschenreuther, N. Morley, D. Ruzic, T. Sketchley, S. Smolentse, R. Woolley, A. Ying, L. Zakharo APEX Electronic Meeting August 14, 000

2 task II scope and approach Scope: exploring high payoff liquid wall concepts that increase the attractieness of fusion energy, with emphasis on understanding the key scientific issues both liquid metals and Flibe, and thin and thick liquid walls that hae the potential to improe the physics performance of plasma Other new APEX concepts that are adanced this year Approach: deelopment and application of much-needed, generic modeling tools for liquid walls and plasma interaction with liquid walls initiation of experiments that address fundamental LW issues identified in last years effort that are key to the understanding of liquid wall phenomena utilization of tools and experimental data to adance the conceptualization of arious LW designs

3 task II/task B presentations Update on Liquid Wall Bulk Plasma Interaction Kaita Update on Intese Lithium Streams in Tokamaks - Zakharo Recent Plasma MHD Results - Kotschenreuther Liquid MHD Modeling and Experiments Morley 1. LM MHD free surface models and current results. Low Conductiity turbulence model deelopment 3. MTOR Facility status 4. UIUC/PPPL small scale experiments 5. FLIHY Facility status 6. LW work for alternate plasma confinement schemes Radwaste Volume and Hazard in LW and Conentional SW concepts Youssef

4 Laminar LM-MHD Models With side-walls or penetrations that break axisymmetry (last year) 1-D Steady-State Analytic Model in constant spanwise field using Hartmann aeraging (insulated side-walls only) 1-D Steady-State Analytic Model in constant surface normal field (can also be applied to axisymmetric cases) with arbitrary backwall conductiity -D Unsteady Boundary Layer Model in a constant spanwise field using Hartmann aeraging (uses surface mapping technique) Axisymmetric models (this year).5-d Unsteady Boundary Layer Model with 3 elocity and 3 ariable field components and applied electric currents (uses surface mapping technique) -D Unsteady Full Solution Model in arbitrarily arying spanwise field with applied electric currents (uses VOF surface tracking technique) NEW DEVELOPMENTS.5-D Unsteady Full Solution Model in arbitrarily arying spanwise field and slowly arying tranerse and streamwise components with applied electric currents (uses VOF surface tracking technique) Participation of HYPERCOMP as an SBIR

5 LM-MHD Model Capability Comparison Analytic D Boundary Layer.5 D Boundary Layer D Full Solution Sidewalls..- model - insulated -conducting Hartmann Ae NO Hartmann Ae NO AXISYMMETRIC - - Unsteady Hydro NO Geometry - cartesian - cylindrical - obstacles NO NO NO (possible) NO Field Components -spanwise -streamwise - transerse Field Gradients - spanwise -streamwise - transerse NO (not simult.) Yes (Very Weak) NO Yes (Very Weak) Mapping NO (not simult) Yes (Very Weak) NO Yes (Very Weak) Mapping (weak) (weak) (gradual) (weak) (weak) Mapping NO AXISYMMETRIC - - NO (possible) NO NO (abitrary) NO NO Free Surface - restrictions Gradual Function Gradual Function Gradual Function VOF Arbitrary Inductie NO NO NO Heat Transfer NO (restricted) Applied Currents NO NO

6 Constant B = 1.5 T D Full Solution..5D Boundary Layer 1/x Field Gradient Region B aries as 1/x from 1.5 T (.5D BL required small applied J for stabilization) 1/x Field Gradient Region B aries as 1/x from 1.5 T applied J = 10 5 A/m

7 .5D Boundary Layer Code Applied to CLiFF-Li Linear Field Gradient Region Flow is ertical, Uo = 10 m/s, Ho = cm B constant at 10 T.. B aries linearly from 10 to 8 T Small effect only seen on CLiFF Outboard Flow with Lithium

8 PLANS for LM-MHD codes CODES AT UCLA 1. Extension of current codes to different geometries. Introduction of optimized solers for poisson equation 3. Application to NSTX, CDX-U, DIII-D, UIUC/PPPL, MTOR 4. COMBINATION CODE with Multi-Component Field Model, Fully Inertial and Viscous Treatment, VOF, and Heat Transfer HYPERCOMP with UCLA 1. Unstructured Meshes and Adaptie Refinement (needed for complex geometries and accurate surface heat transfer). Extension to 3D arbitrary geometries 3. Parallelization

9 K-e turbulence modeling for low-conductiity high Pr liquids KE MHD Turbulence model: ; ] x K ) [( x x x K t K Dissipation em Diffusion j K t j oduction Pr j i t j j ε ε σ ν ν = ν ; K K C ] x ) [( x x K C x t em j t j j i t 1 j j ε ε ε ε ε σ ν ν ν ε = ε ε ε ; / K C t ε = ν ν Modeling of the Joule dissipation term:. )] x x ( B ) x1 x ( B ) x x ( B B B B B B B B B B )K B B [(B II I D D em ϕ ϕ ϕ ϕ ϕ ϕ ρ σ = ε

10 IMPROVING THE k-e TURBULENCE MODEL The expression includes terms with elocity pulsations (D I ) and electric field fluctuations (D II ), which come from two components in Ohms law: σ V B0 and σ ϕ respectiely. In channel flows with a weak transerse magnetic field, the turbulence structure is close to that in ordinary flows where streamwise ortices dominate. For such ortices, the electric potential almost does not ary, and hence ε em D I. In the case of a strong magnetic field, transition to a -D state occurs, in which turbulent eddies are elongated in the field direction, so that D II -D I and ε em =0 in the limit. This gies ground for modeling ε em in the equations for K and ε σ σ as C 3 B0K, C4 B0ε ρ ρ respectiely with C 3 and C 4 from 0 to (depending on flow parameters). The choice of C 3 and C 4 is based on existing experimental and new DNS-MHD data from collaboration with Professors Satake and Kunugi

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18 MTOR Magnetic Torus, LM-MHD Facility Inside iew of the 4 coil magnetic torus, Coil ID = 80 cm

19 MTOR Staged Implementation Stage 1 (this summer) 4 coil torus, 1800 A per coil, ~600 kw Surface normal fields built with permanent magnets Bi-Pb-In-Sn-Cd liquid metal with max flowrate ~1.5 l/s Applied electric currents > 1000 A possible. Stage Polodial field generation with long pulse internal conductors (simulate plasma current) Toroidal field magnets run at full rated current, 3664 A/coil Stage 3 Flow loop upgrade to Ga or Na alloy at ~5 l/s

20 Facility Specifications for M-Tor 4 Coil Configuration Total Volts (with water cooling) Required Power (with water cooling) Coil Connection (Current per Coil) Stage I Stage II Volts 714 Volts 600 KW.6 MW strings in parallel (1800 A) 78 mm (390,1176) T ( ) 1 string in series (3664 A) Major Radius, Midplane (Inboard, Outboard) 78 mm (390,1176) Toroidal Field, Midplane T (Inboard, Outboard) (1.63, 0.418) Power Within Current NO with water Capability with N Powered By PPPL PS NO with water with N

21 Test Section First Experimental Campaign Flat, insulated plane,oriented for poloidal flow Adjustable sidewall position Existing Bi-Pb-In alloy as working metal Applied electric current at inlet/outlet Detachable permanent magnets for poloidal field simulation Flow height measured with ultrasound, micrometer, and fast photography Effects Explore effect of elongation of flow along B field (model alidation) Explore effect of finite surface-normal fields (model alidation) Explore MP and other EMP/R ideas (model alidation) Explore diamagnetic effect in 1/R field as much as possible (model alidation) Explore dierging flow area effect and effect of conducting penetrations

22 II.1 Exploration of thin and thick LM wall concepts (continued) New experimental test of magnetic propulsion under deelopment after PPPL isit to Uniersity of Illinois last May: Toroidally Symmetric Flowing Liquid Metal Test Facility. Liquid gallium flows down centerpost in an NSTX geometry. B on the center post surface = 0. Tesla. Current of 00 A can flow through the flowing metal in a ariety of directions. Gallium and power supplies loaned by PPPL to Uniersity of Illinois for this experiment. Picture of facility shown on next figure.» Only one winding is in place: total of 65 windings are planned.

23 II.1 Exploration of thin and thick LM wall concepts (continued) Toroidally Symmetric Flowing Liquid Metal Test Facility at the Uniersity of Illinois.

24 FLIRE Experiment Tests Liquid flows down two chutes and merges to form a seal. Will be used to test ion pumping characteristics of flow liquids

25 FLIRE Testing with Liquid Gallium Seal region

26 Flibe Flow and Heat Transfer Experiments FliHy facility water/koh discharge and flowloop Various open channel test sections planned (cured sections, flat long sections and flow obstructions to simulate penetrations) KOH to add electrical conductiity and suppress surface aporization Flexible for IFE and Monbusho collaboration needs Potential to do low flowrate experiments in the Japanese HTS loop Status: awaiting construction

27 FliHy Facility:Inclined Plate Experiment Inestigate heat transfer at surface and basic hydrodynamics of open channel flow oer inclined plate. Uses dye technique, IR camera, and ultrasonic diagnostics. Working fluid: Water

28 Surface Mass Transfer Measurements Heat-transport-related hydrodynamic parameters of free surface regimes for flows similar to APEX or Cliff design will be determined experimentally. Heat transfer at the surface of these open channel flows is modeled by a set of hydrodynamic parameters, which can be unified by the mathematical definition of the turbulent Prandtl number. Pr t turbulentmomentumtransfer = turbulentheat transfer T u υt y = = α u t T y

29 Visualization Method In turbulent flow, mass (and heat) transport are dominated by turbulent diffusion. To determine the total diffusion coefficient D eff = D D t, the mass transport equation can be soled numerically or analytically in the form: δ(n)=c(d eff ) Where δ(n) is the thickness of the concentration boundary layer, in relation to the back wall or the aerage height (position) of the surface. This yields D eff (y), the distribution for total diffusion coefficient By using the solution in the form δ(n)=f(d eff ) along with experimental data for δ(n), then D t (y) can be obtained.

Ultrasonic Flow Height Measurements Transducer mounting - open channel Fluid height measurement: Gies bulk elocity when combined with flow meter data. Hence, also gies Fr.

30 Ultrasonic Flow Height Measurements Transducer mounting - open channel Fluid height measurement: Gies bulk elocity when combined with flow meter data. Hence, also gies Fr. Yields Re when combined with temperature (iscosity and density table) data. Statistically quantifies surface wainess and Pr t distribution hypothesis. Sensitie to ± inch (of calibrated span).

31 Verifying the Completed Model σ T Re=13,000 - Re=17,900 - Re=0,00 - Re=3,100 - (36) y/h Figure: Turbulent Prandtl number growth near free surface (courtesy Smolentse) Pr t is the remaining localized quantity that determines T in the k-ε model, hence the alue of Pr t is critically important to model free surface temperature change. With a well quantified Pr t, a completed k-ε model can proceed to benchmark itself against real free surface temperature data for smooth or way surfaced flow. This data comes from infrared ideography, sensitie to <0.07ºC, in unison with surface heating.

Infrared Surface Temperature Measurement Initial FLIR camera filter is calibrated to water s surface emissiity. Hence, it measures the surface temperature field.

32 Infrared Surface Temperature Measurement Initial FLIR camera filter is calibrated to water s surface emissiity. Hence, it measures the surface temperature field. Concae surface waes are not foreseen as a limiting phenomenon by FLIR. Such wae s emissiity shift is within the tolerance of a calibrated filter. For extra calibration, bulk temperatures are sampled using thermocouples, as well as from flow meter s thermometer. Possibility of collaboration on use of system from Sandia Labs (ia Mike Ulrichson).

33 task II alternate confinement schemes The following people hae agreed to discuss the APEX role on LWs for alternate plasma confinement schemes: Morley, Kotschenreuther, Moir, Kaita, Wong, Ulrickson, Ying, Woolley We were unable to find a time to get together of the past couple weeks, and so this remains as a task II action item.

CHALLENGE: MAGNETOHYDRODYNAMICS

CHALLENGE: MAGNETOHYDRODYNAMICS Turbulence / free surface interaction produces key phenomena - anisotropic near-surface turbulence Turbulent production dominated by the generation of wall eections, formation of spanwise upsurging vortices